Jock itch (tinea cruris) is a common, preventable fungal infection mainly affecting the groin, inner thighs, and buttocks. These are warm parts of the body where moisture can accumulate, providing the ideal environment for the fungi to grow.
Jock itch is so-named because it commonly affects athletes who pass the fungus to others in locker rooms through wet towels and clothing. You can also get it if you have athlete's foot and touch your foot and then your groin. People who sweat heavily or live in moist, tropical climates are also vulnerable.
Jock itch rarely goes away on its own. Most infections can be cleared with the twice-daily application of an over-the-counter (OTC) antifungal cream or ointment for one to three weeks. If these don't help, a prescription antifungal cream or oral antifungal drug may be needed.
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What Is Jock Itch and How Is It Spread?
Jock's itch is mainly caused by a fungus (yeast) called Trichophyton rubrum. This is the same fungus that can cause athlete's foot (tinea pedis), ringworm (tinea corporis), scalp ringworm (tinea capitis), and fungal nail infections (tinea unguium).
Other, less common fungi can also cause jock itch, including strains of Epidermophyton, Nannizzia, Paraphyton, and Lophophyton. The fungi are collectively known as dermatophytes. and the infection they cause is referred to as dermatophytosis.
The fungi that cause jock itch thrive in warm, moist environments. It is both highly contagious and robust, able to penetrate and persist in the uppermost layers of the skin. Once an infection is established, it can spread as fungal spores are shed onto surrounding skin.
The common routes of transmission for jock itch include:
- Person to person through skin contact
- Shared contaminated towels or clothing
- Autoinoculation (the transfer of the fungus from one part of your body to another, such as scratching your scalp if you have tinea capitis and then your groin)
Risk Factors for Jock Itch
Jock itch can affect anyone but is more common in certain groups, including:
- Males
- Younger people, including teens and young adults
- People who sweat heavily (known as hyperhidrosis)
- People who wear tight underwear or pants
- People with obesity (who tend to sweat heavily and have more skin folds)
- Immunocompromised people, including those with untreated HIV
- People with uncontrolled diabetes
- People with athlete's foot
Jock itch is more common in the summer, though it can occur at any time of year.
Signs and Symptoms of Jock Itch
Although jock itch is caused by the same fungus as ringworm, it can develop differently in the groin. Unlike ringworm, which spreads outward in a ring-shaped pattern, jock itch can cause a more haphazardly shaped rash.
This is because fungal growth follows the pattern of moisture in the groin. Moreover, if skin on both sides of a skin fold presses against each other, it can even cause a rash with a symmetrical, mirrored pattern.
Common symptoms of jock itch include:
- A spreading rash that typically starts in the crease of the groin before moving to the inner thigh and buttocks
- A rash whose center is clearer than the edges
- A scaly, red border with small blisters
- A reddish or reddish-brown interior
- Persistent itchiness
- Burning or stinging
Can Jock Itch Affect My Penis and Scrotum?
Jock itch rarely affects the scrotum or penis. If those areas are affected, it is more likely due to Candida albicans, the same fungus that causes vaginal yeast infections.
How Jock Itch Is Diagnosed
Most dermatologists can diagnose jock itch by the appearance of the rash. Even so, they will likely want to confirm the diagnosis with a KOH test.
The KOH test involves the application of a chemical called potassium hydroxide (KOH) to a skin scraping, which dissolves all cells except fungi. This makes it easier to view the fungus under the microscope. Special stains such as Parker's blue ink can the fungus even more visible.
A Wood's lamp, commonly used to diagnose other fungal skin infections, is less helpful with jock itch. This is because Trichophyton fungi do not fluoresce and change colors when exposed to ultraviolet light like other fungi do.
Skin Conditions Jock Is Mistaken For
If there is any doubt as to whether T. rubrum is involved, a skin scraping can be cultured (grown) in the lab to confirm the diagnosis, This will help differentiate it from skin conditions with a similar appearance, such as:
- Allergic contact dermatitis (a scaly skin condition caused by contact with an allergen)
- Irritant contact dermatitis (a scaly skin condition caused by contact with an irritant, like nickel)
- Erythrasma (caused by a bacterial called Corynebacterium)
- Pustular psoriasis (a form of psoriasis often seen in the groin and genital)
- Candidal intertrigo (a yeast infection in skin folds, more common in people with obesity)
How to Get Rid of Jock Itch
Jock itch is typically treated with topical antifungal creams or ointments applied directly to the affected skin. These control the infection by disrupting the outer shell of the fungus, causing the insides to seep out.
Four OTC topical antifungals are commonly used for this:
- Lamisil (terbinafine)
- Tinactin (tolnaftate)
- Lotrimin (clotrimazole)
- Micatin (miconazole)
Apply the cream or ointment to the rash and surrounding skin, twice daily, washing your hands immediately after. With consistent use, the rash will generally clear in one to three weeks. Continue application one week after the rash has fully cleared to ensure it is completely gone.
Many people with jock itch also have athlete's foot and can use the same cream or ointment for both. However, athlete's foot treatment can take longer to resolve.
Note that some of these OTC antifungals are available as powders and sprays, which are generally reserved for the treatment of athlete's foot rather than jock itch.
Home Remedies
In addition to over-the-counter treatments for jock itch, there are a few things you can do at home to manage the infection:
- Keep the affected skin clean and dry. Wash and dry at least once daily and after activities that cause sweating, such as sports.
- Use a gentle soap and plain water. An antibacterial soap generally isn't necessary. Alcohol-based cleansers should be avoided as they can irritate the skin and cause stinging.
- Do not use the same towel to dry the groin as the rest of your body. This can pass the infection to other parts of your body.
- Avoid scratching. If you find this hard, clip your fingernails short, calm the itch with a cold compress, or apply Calamine lotion to the affected tissues.
- Change your pants and underwear daily. If you are prone to sweating, try wearing underwear made from moisture-wicking fabrics, and promptly change out of them whenever sweaty or wet.
Prescriptions
Most cases of jock itch are easily treated with OTC antifungals. However, certain fungal types are harder to treat, as are people who are severely immunocompromised.
In such cases, topical antifungals may need to be combined with a course of oral antifungals. These include drugs like:
- Diflucan (fluconazole)
- Grifulvin (griseofulvin)
- Sporanox (itraconazole)
- Terbinex (terbinafine)
Diflucan and Grifulvin are typically used daily for two to four weeks, while Sporanox and Terbinex are typically used once daily for one to two weeks.
When to See a Healthcare Provider
If jock itch does not improve after a week of OTC treatments, see your healthcare provider for stronger medications. You should also see a doctor if the rash develops blisters.
A severe case of jock itch may require treatment with corticosteroids, such as hydrocortisone, to reduce inflammation. Even so, do not use steroids unless under medical supervision. The inappropriate of steroids can impair the immune system and further promote fungal growth.
How to Prevention Jock Itch
There are several simple things you can do to prevent jock itch from occurring or recurring, including:
- Wear loose-fitting clothing made of cotton or synthetic materials designed to wick moisture.
- Avoid sharing clothing and towels or washcloths.
- Allow the groin to dry completely after showering before putting on underwear and clothes.
- Use antifungal powders or sprays once daily to prevent infection.
- If you wear a jockstrap for sports, always wash the strap and cup between uses.
Summary
Jock itch (tinea cruris) is a fungal infection of the groin caused by the same fungi that cause athlete's foot and ringworm. The scaly, itchy rash tends to start in the groin and spread to nearby areas (like the buttocks or inner thigh) wear moisture accumulates.
Jock itch can be diagnosed under the microscope with a KOH test that helps isolate the fungus from other cells in a skin scraping. Most cases of jock itch can be effectively treated with over-the-counter topical antifungals, but difficult cases may also need a course of oral antifungals.